1. Field of the Invention
The invention relates to a slide mount for telescopic parts comprising an adjustable slipper of substantially large surface area, disposed between the sliding surface areas of the telescopic parts.
2. Description of the Prior Art
Telescopic jibs such as, for example, those of stationary or mobile cranes are made up of several nested telescopic parts which can be extended in lengthening the jib. The telescopic parts are slidably mounted in each other, the inner telescopic part being guided in a collar secured to the front section of the outer telescopic part and in the base portion of the inner telescopic part at the shank piece of the outer telescopic part. Extension of the inner telescopic part thus results in mounting loads in the collar of the outer telescopic part and in the base portion of the inner telescopic part which attain peak values at the base of the collar and at the top of the base portion of the inner telescopic part.
To enable the telescopic parts to be extended and to handle the cited mounting loads, prior art provides a slide mount in each case between the two telescopic parts. For example, in the lower collar region and in the upper rear base region of a substantially rectangular beam, slipper blocks are inserted in the corners and are adapted to the shape of the gap between collar and inner telescopic part and on which the telescopic parts are able to slide on and in each other.
The drawback in the case of slipper blocks provided only in the corners is the fact that introducing the force from the inner telescopic part into the collar mainly takes place over only a portion of the existing surface area of the sliding blocks, mainly in the outer slipper surface areas adjoining the downsweeps of the inner telescopic part. Due to the resulting high contact pressure forces in conjunction with the minor width in this case a relatively long slipper is needed which may necessitate compensation in the longitudinal axis of the jib. In addition to this additional bending stresses occur in the downsweep portion of the inner telescopic part as a function of the bending radius and material of the slipper. Furthermore, the slipper blocks need to be designed to stay in position, for example, by adapting surface curvature downsweep relatively precisely, or by scalloping the collar to receive the blocks.
From DE 296 13 042 U1 a slide mount for nested dish-shaped bodies is known and intended for use in the telescopic jib of a mobile crane. This slide mount consists of dished strips of a plastics material or some other material having good sliding properties, the strips or plates comprising slats articulately connected to each other by their longitudinal sides. What is proposed in this case is thus a kind of "sliding chain" interposed between the telescopic parts.
Such chain-like slide mounts have the drawback that, unless special precautions are taken, they fail to remain in place, i.e. they tend to become displaced in the circumferential direction of the telescopic parts, this being the reason why, for instance, stops need to be provided against the movement of these slide mounts between the telescopic parts.
A further disadvantage of this mounting design and also of the block mount cited above is that adapting the slippers to special requirements, for instance deviations in production (tolerances) or influencing the location of the telescopic parts with respect to each other via the slide mounts is highly complicated, since the slide mounts have a given position and thickness which cannot be simply adapted or changed.